For to be vexed at anything which happens is a separation of ourselves from nature, in some part of which the natures of all other things are contained. In the next place, the soul does violence to itself when it turns away from any man, or even moves towards him with the intention of injuring, such as are the souls of those who are angry. In the third place, the soul does violence to itself when it is overpowered by pleasure or by pain. Fourthly, when it plays a part, and does or says anything insincerely and untruly. Fifthly, when it allows any act of its own and any movement to be without an aim, and does anything thoughtlessly and without considering what it is, it being right that even the smallest things be done with reference to an end; and the end of rational animals is to follow the reason and the law of the most ancient city and polity.
The quote: Of human life the time is a point, and the substance is in a flux, and the perception dull, and the composition of the whole body subject to putrefaction, and the soul a whirl, and fortune hard to divine, and fame a thing devoid of judgment.
And, to say all in a word, everything which belongs to the body is a stream, and what belongs to the soul is a dream and vapor, and life is a warfare and a stranger's sojourn, and after fame is oblivion. What then is that which is able to conduct a man? One thing, and only one, philosophy.